<PAGE>

                                                                    EXHIBIT 10.1

                             ARBINET HOLDINGS, INC.
                              AMENDED AND RESTATED
                            1997 STOCK INCENTIVE PLAN

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                Page
                                                                                ----
<S>                                                                              <C>
ARTICLE I   GENERAL..........................................................     1
       1.1  Purpose .........................................................     1
       1.2  Administration ..................................................     1
       1.3  Persons Eligible for Awards......................................     2
       1.4  Types of Awards Under Plan.......................................     2
       1.5  Shares Available for Awards......................................     2
       1.6  Definitions of Certain Terms.....................................     3
ARTICLE II  AWARDS UNDER THE PLAN............................................     5
       2.1  Agreements Evidencing Awards.....................................     5
       2.2  No Rights as a Shareholder.......................................     5
       2.3  Grant of Stock Options, Stock Appreciation Rights and Dividend
            Equivalent Rights................................................     5
       2.4  Exercise of Options and Stock Appreciation Rights................     7
       2.5  Termination of Employment; Death.................................     8
       2.6  Grant of Restricted Stock........................................     9
       2.7  Grant of Restricted Stock Units..................................    10
       2.8  Other Stock-Based Awards.........................................    10
       2.9  Stock in Lieu of Cash............................................    11
       2.10 Grant of Dividend Equivalent Rights..............................    11
ARTICLE III MISCELLANEOUS....................................................    11
       3.1  Amendment of the Plan; Modification of Awards....................    11
       3.2  Tax Withholding..................................................    12
       3.3  Restrictions.....................................................    12
       3.4  Nonassignability.................................................    14
       3.6  Requirement of Notification Upon Disqualifying Disposition
            Under Section 42 l(b) of the Code................................    14
       3.7  Right of Discharge Reserved......................................    14
       3.8  Nature of Payments...............................................    14
</TABLE>

                                        i

<PAGE>

<TABLE>
<CAPTION>
                                                                                Page
                                                                                ----
<S>                                                                              <C>
       3.9  Non-Uniform Determinations.......................................    15
       3.10 Other Payments or Awards.........................................    15
       3.11 Section Headings.................................................    15
       3.12 Effective Date and Term of Plan..................................    15
       3.13 Governing Law....................................................    15
</TABLE>

                                       ii

<PAGE>

                             ARBINET HOLDINGS, INC.
                              AMENDED AND RESTATED
                            1997 STOCK INCENTIVE PLAN

                                    ARTICLE I
                                     GENERAL

1.1  Purpose

     The purpose of the Arbinet Holdings, Inc. 1997 Amended and Restated Stock
Incentive Plan (the "Plan") is to provide for officers, other employees and
directors of, and consultants to, Arbinet Holdings, Inc. (the "Company") and its
subsidiaries an incentive (a) to enter into and remain in the service of the
Company, (b) to enhance the long-term performance of the Company, and (c) to
acquire a proprietary interest in the success of the Company.

1.2  Administration

          1.2.1 Subject to Section 1.2.6, the Plan shall be administered by the
Compensation Committee (the "Committee") of the board of directors of the
Company (the "Board"), which shall consist of not less than two directors. The
members of the Committee shall be appointed by, and serve at the pleasure of,
the Board. To the extent required for transactions under the Plan to qualify for
the exemptions available under Rule 16b-3 ("Rule 16b-3") promulgated under the
Securities Exchange Act of 1934 (the "1934 Act"), all actions relating to awards
to persons subject to Section 16 of the 1934 Act shall be taken by the Board
unless each person who serves on the Committee is a "non-employee director"
within the meaning of Rule 16b-3 or such actions are taken by a sub-committee of
the Committee (or the Board) comprised solely of "non-employee directors." To
the extent required for compensation realized from awards under the Plan to be
deductible by the Company pursuant to section 162(m) of the Internal Revenue
Code of 1986 (the "Code"), the members of the Committee shall be "outside
directors" within the meaning of section 162(m).

          1.2.2 The Committee shall have the authority (a) to exercise all of
the powers granted to it under the Plan, (b) to construe, interpret and
implement the Plan and any Plan Agreements executed pursuant to Section 2. 1,
(c) to prescribe, amend and rescind rules and regulations relating to the Plan,
including rules governing its own operations, (d) to make all determinations
necessary or advisable in administering the Plan, (e) to correct any defect,
supply any omission and reconcile any inconsistency in the Plan, and (f) to
amend the Plan to reflect changes in applicable law.

          1.2.3 Actions of the Committee shall be taken by the vote of a
majority of its members. Any action may be taken by a written instrument signed
by a majority of the Committee members, and action so taken shall be fully as
effective as if it had been taken by a vote at a meeting.

                                       1

<PAGE>

          1.2.4 The determination of the Committee on all matters relating to
the Plan or any Plan Agreement shall be final, binding and conclusive.

          1.2.5 No member of the Committee shall be liable for any action or
determination made in good faith with respect to the Plan or any award
therunder.

          1.2.6. Notwithstanding anything to the contrary contained herein: (a)
until the Board shall appoint the members of the Committee, the Plan shall be
administered by the Board; and (b) the Board may, in its sole discretion, at any
time and from time to time, grant awards or resolve to administer the Plan; and
(c) the Chief Executive Officer of the Company shall have the authority to
determine the vesting period and expiration date of options awarded under the
Plan. In any of the foregoing events, the Board or the Chief Executive Officer
shall have all of the authority and responsibility granted to the Committee
herein.

1.3  Persons Eligible for Awards

     Awards under the Plan may be made to such directors, officers and other
employees of the Company and its subsidiaries (including prospective employees
conditioned on their becoming employees), and to such consultants to the Company
and its subsidiaries (collectively, "key persons") as the Committee shall in its
discretion select.

1.4  Types of Awards Under Plan

     Awards may be made under the Plan in the form of (a) incentive stock
options (within the meaning of section 422 of the Code), (b) nonqualified stock
options, (c) stock appreciation rights, (d) dividend equivalent rights, (e)
restricted stock, (f) restricted stock units and (g) other stock-based awards,
all as more fully set forth in Article II. The term "award" means any of the
foregoing. No incentive stock option may be granted to a person who is not an
employee of the Company on the date of grant.

1.5  Shares Available for Awards

          1.5.1 The total number of shares of common stock of the Company, par
value $.001 per share ("Common Stock"), which may be transferred pursuant to
awards granted under the Plan shall be 12,500,000 shares (prior to giving effect
to the stock split approved by the Board in March 2000). On January 1 of each
year, commencing on January 1, 2001, the number of shares of common stock
available for issuance shall increase by the lesser of: (i) 2,000,000 shares;
(ii) 3% of the then outstanding shares of common stock; or (iii) a number of
shares determined by the Board. Such shares may be authorized but unissued
Common Stock or authorized and issued Common Stock held in the Company's
treasury or acquired by the Company for the purposes of the Plan. The Committee
may direct that any stock certificate evidencing shares issued pursuant to the

                                       2

<PAGE>

Plan shall bear a legend setting forth such restrictions on transferability as
may apply to such shares pursuant to the Plan.

          1.5.2 Subject to any required action by the shareholders of the
Company, the number of shares of Common Stock covered by each outstanding award,
the number of shares available for awards, the number of shares that may be
subject to awards to any one employee, and the price per share of Common Stock
covered by each such outstanding award shall be proportionately adjusted for any
increase or decrease in the number of issued shares of Common Stock resulting
from a stock split, reverse stock split, stock dividend, combination or
reclassification of the Common Stock, or any other increase or decrease in the
number of issued shares of Common Stock effected without receipt of
consideration by the Company; provided, however, that conversion of any
convertible securities of the Company shall not be deemed to have been "effected
without receipt of consideration." Such adjustment shall be made by the
Committee, whose determination in that respect shall be final, binding and
conclusive. Except as expressly provided herein, no issuance by the Company of
shares of stock of any class, or securities convertible into shares of stock of
any class, shall affect, and no adjustment by reason thereof shall be made with
respect to, the number or price of shares of Common Stock subject to an award.
After any adjustment made pursuant to this Section 1.5.2, the number of shares
subject to each outstanding award shall be rounded to the nearest whole number.

          1.5.3 Except as provided in this Section 1.5 and in Section 2.3.7,
there shall be no limit on the number or the value of the shares of Common Stock
that may be subject to awards to any individual under the Plan.

1.6  Definitions of Certain Terms

          1.6.1 The "Fair Market Value" of a share of Common Stock on any day
shall be determined as follows:

               (a) If the principal market for the Common Stock (the Market") is
a national securities exchange or the National Association of Securities Dealers
Automated Quotation System ("NASDAQ") National Market, the last sale price or,
if no reported sales take place on the applicable date, the average of the high
bid and low asked price of Common Stock as reported for such Market on such date
or, if no such quotation is made on such date, on the next preceding day on
which there were quotations, provided that such quotations shall have been made
within the ten (10) business days preceding the applicable date;

               (b) If the Market is a Market other than the NASDAQ National
Market, the average of the high bid and low asked price for the Common Stock on
the applicable date, or, if no such quotations shall have been made on such
date, on the next

                                       3

<PAGE>

preceding day on which there were quotations, provided that such quotations
shall have been made within the ten (10) business days preceding the applicable
date; or,

               (c) In the event that neither paragraph (a) nor (b) shall apply,
the Fair Market Value of a share of Common Stock on any day shall be determined
in good faith by the Committee.

          1.6.2 The term "incentive stock option" means an option that is
intended to qualify for special federal income tax treatment pursuant to
sections 421 and 422 of the Code, as now constituted or subsequently amended, or
pursuant to a successor provision of the Code, and which is so designated in the
applicable Plan Agreement. Any option that is not specifically designated as an
incentive stock option shall under no circumstances be considered an incentive
stock option. Any option that is not an incentive stock option is referred to
herein as a "nonqualified stock option."

          1.6.3 The term "employment" means, in the case of a grantee of an
award under the Plan who is not an employee of the Company, the grantee's
association with the Company or a subsidiary as a director, consultant or
otherwise.

          1.6.4 A grantee shall be deemed to have a "termination of employment"
upon ceasing to be employed by the Company and all of its subsidiaries or by a
corporation assuming awards in a transaction to which section 424(a) of the Code
applies. The Committee may in its discretion determine (a) whether any leave of
absence constitutes a termination of employment for purposes of the Plan, (b)
the impact, if any, of any such leave of absence on awards theretofore made
under the Plan, and (c) when a change in a non-employee's association with the
Company constitutes a termination of employment for purposes of the Plan. The
Committee shall have the right to determine whether the termination of a
grantee's employment is a dismissal for cause (as defined herein) and the date
of termination in such case, which date the Committee may retroactively deem to
be the date of the action that is cause for dismissal. Such determinations of
the Committee shall be final, binding and conclusive.

          1.6.5 The term "cause," when used in connection with termination of a
grantee's employment, shall have the meaning set forth in any then-effective
employment agreement between the grantee and the Company or a subsidiary
thereof. In the absence of such an employment agreement, "cause" means: (i) the
gross neglect or willful failure or refusal of the Optionee to perform
Optionee's duties under any agreement between the Optionee and the Company
(other than as a result of total or partial incapacity due to physical or mental
illness); (ii) the engaging by Optionee in misconduct which is injurious to the
Company, monetarily or otherwise; (iii) perpetration of an intentional and
knowing fraud against or affecting the Company or any customer, client, agent,
or employee thereof; (iv) any willful or intentional act that could reasonably
be expected to injure the reputation, business, or business relationships of the
Company or Employee's reputation or business relationships; (v) conviction
(including conviction on a nolo

                                       4

<PAGE>

contendere plea) of a felony or any crime involving, in the good faith judgment
of the Company, fraud, dishonesty or moral turpitude; or (vi) the breach of any
covenant by the Optionee to the Company relating to noncompetition,
nonsolicitation, nondisclosure of proprietary information or surrender of
records, inventions or patents.

                                   ARTICLE II
                              AWARDS UNDER THE PLAN

2.1  Agreements Evidencing Awards

     Each award granted under the Plan (except an award of unrestricted stock)
shall be evidenced by a written agreement ("Plan Agreement") which shall contain
such provisions as the Committee in its discretion deems necessary or desirable.
Such provisions may include, without limitation, a requirement that the grantee
become a party to a shareholders' agreement with respect to any shares of Common
Stock acquired pursuant to the award, a requirement that the grantee acknowledge
that such shares are acquired for investment purposes only, a right of first
refusal exercisable by the Company in the event that the grantee wishes to
transfer any such shares, and a call right exercisable by the Company following
the termination of employment. By accepting an award pursuant to the Plan, a
grantee thereby agrees that the award shall be subject to all of the terms and
provisions of the Plan and the applicable Plan Agreement.

2.2  No Rights as a Shareholder

     No grantee of an option or stock appreciation right (or other person having
the right to exercise such award) shall have any of the rights of a shareholder
of the Company with respect to shares subject to such award until the issuance
of a stock certificate to such person for such shares. Except as otherwise
provided in Section 1.5.3, no adjustment shall be made for dividends,
distributions or other rights (whether ordinary or extraordinary, and whether in
cash, securities or other property) for which the record date is prior to the
date such stock certificate is issued.

2.3  Grant of Stock Options, Stock Appreciation Rights and Dividend Equivalent
     Rights

          2.3.1 The Committee may grant incentive stock options and nonqualified
stock options (collectively, "options") to purchase shares of Common Stock from
the Company, to such key persons, in such amounts and subject to such terms and
conditions, as the Committee shall determine in its discretion, subject to the
provisions of the Plan.

          2.3.2 The Committee may grant stock appreciation rights to such key
persons, in such amounts and subject to such terms and conditions, as the
Committee shall determine in its discretion, subject to the provisions of the
Plan. Stock appreciation rights may be granted in connection with all or any
part of, or independently of, any

                                       5

<PAGE>

option granted under the Plan. A stock appreciation right granted in connection
with a nonqualified stock option may be granted at or after the time of grant of
such option. A stock appreciation right granted in connection with an incentive
stock option may be granted only at the time of grant of such option.

          2.3.3 The grantee of a stock appreciation right shall have the right,
subject to the terms of the Plan and the applicable Plan Agreement, to receive
from the Company an amount equal to (a) the excess of the Fair Market Value of a
share of Common Stock on the date of exercise of the stock appreciation right
over (b) the exercise price of such right as set forth in the Plan Agreement (or
over the option exercise price if the stock appreciation right is granted in
connection with an option), multiplied by (c) the number of shares with respect
to which the stock appreciation right is exercised. Payment upon exercise of a
stock appreciation right shall be in cash or in shares of Common Stock (valued
at their Fair Market Value on the date of exercise of the stock appreciation
right) or both, all as the Committee shall determine in its discretion. Upon the
exercise of a stock appreciation right granted in connection with an option, the
number of shares subject to the option shall be correspondingly reduced by the
number of shares with respect to which the stock appreciation right is
exercised. Upon the exercise of an option in connection with which a stock
appreciation right has been granted, the number of shares subject to the stock
appreciation right shall be correspondingly reduced by the number of shares with
respect to which the option is exercised.

          2.3.4 Each Plan Agreement with respect to an option shall set forth
the amount (the "option exercise price") payable by the grantee to the Company
upon exercise of the option evidenced thereby. The option exercise price per
share shall be determined by the Committee in its discretion; provided, however,
that the option exercise price of an incentive stock option shall be at least
100% of the Fair Market Value of a share of Common Stock on the date the option
is granted, and provided further that in no event shall the option exercise
price be less than the par value of a share of Common Stock.

          2.3.5 Each Plan Agreement with respect to an option or stock
appreciation right shall set forth the periods during which the award evidenced
thereby shall be exercisable, whether in whole or in part. Such periods shall be
determined by the Committee in its discretion; provided, however, that no
incentive stock option (or a stock appreciation right granted in connection with
an incentive stock option) shall be exercisable more than 10 years after the
date of grant.

          2.3.6 The Committee may in its discretion include in any Plan
Agreement with respect to an option (the "original option") a provision that an
additional option (the "additional option") shall be granted to any grantee who,
pursuant to Section 2.4.3(b), delivers shares of Common Stock in partial or full
payment of the exercise price of the original option. The additional option
shall be for a number of shares of Common Stock equal to the number thus
delivered, shall have an exercise price equal to the Fair

                                       6

<PAGE>

Market Value of a share of Common Stock on the.date of exercise of the original
option, and shall have an expiration date no later than the expiration date of
the original option. In the event that a Plan Agreement provides for the grant
of an additional option, such Agreement shall also provide that the exercise
price of the original option be no less than the Fair Market Value of a share of
Common Stock on its date of grant, and that any shares that are delivered
pursuant to Section 2.4.3(b) in payment of such exercise price shall have been
held for at least six months.

          2.3.7 To the extent that the aggregate Fair Market Value (determined
as of the time the option is granted) of the stock with respect to which
incentive stock options granted under this Plan and all other plans of the
Company and any subsidiary are first exercisable by any employee during any
calendar year shall exceed the maximum limit (currently, $100,000), if any,
imposed from time to time under section 422 of the Code, such options shall be
treated as nonqualified stock options.

          2.3.8 Notwithstanding the provisions of Sections 2.3.4 and 2.3.5, to
the extent required under section 422 of the Code, an incentive stock option may
not be granted under the Plan to an individual who, at the time the option is
granted, owns stock possessing more than 10% of the total combined voting power
of all classes of stock of his employer corporation or of its parent or
subsidiary corporations (as such ownership may be determined for purposes of
section 422(b)(6) of the Code) unless (a) at the time such incentive stock
option is granted the option exercise price is at least 110% of the Fair Market
Value of the shares subject thereto and (b) the incentive stock option by its
terms is not exercisable after the expiration of five (5) years from the date it
is granted.

2.4  Exercise of Options and Stock Appreciation Rights

     Subject to the provisions of this Article 11, each option or stock
appreciation right granted under the Plan shall be exercisable as follows:

          2.4.1 An option or stock appreciation right shall become exercisable
as determined by the Committee and set forth in a Plan Agreement, and once it
becomes exercisable shall remain exercisable until expiration, cancellation or
termination of the award.

          2.4.2 Unless the applicable Plan Agreement otherwise provides, an
option or stock appreciation right may be exercised from time to time as to all
or part of the shares as to which such award is then exercisable (but, in any
event, only for whole shares). A stock appreciation right granted in connection
with an option may be exercised at any time when, and to the same extent that,
the related option may be exercised. An option or stock appreciation right shall
be exercised by the filing of a written notice with the Company, on such form
and in such manner as the Committee shall prescribe.

                                       7

<PAGE>

          2.4.3 Any written notice of exercise of an option shall be accompanied
by payment for the shares being purchased. Such payment shall be made: (a) by
certified or official bank check (or the equivalent thereof acceptable to the
Company) for the full option exercise price; or (b) unless the applicable Plan
Agreement provides otherwise, by delivery of shares of Common Stock acquired at
least six months prior to the option exercise date and having a Fair Market
Value (determined as of the exercise date) equal to all or part of the option
exercise price and a certified or official bank check (or the equivalent thereof
acceptable to the Company) for any remaining portion of the full option exercise
price; (c) on a "cashless" basis, by stating in the exercise notice the number
of shares the Optionee elects to purchase pursuant to such exercise (in which
case the Optionee shall receive a number of shares equal to the number the
Optionee would have received upon such exercise for cash less such number of
shares as shall then have a Fair Market Value in the aggregate equal to the
exercise price due in respect of such exercise); or (d) at the discretion of the
Committee and to the extent permitted by law, by such other provision as the
Committee may from time to time prescribe.

          2.4.4 Promptly after receiving payment of the full option exercise
price, or after receiving notice of the exercise of a stock appreciation right
for which payment will be made partly or entirely in shares, the Company shall,
subject to the provisions of Section 3.3 (relating to certain restrictions),
deliver to the grantee or to such other person as may then have the right to
exercise the award, a certificate or certificates for the shares of Common Stock
for which the award has been exercised. If the method of payment employed upon
option exercise so requires, and if applicable law permits, an optionee may
direct the Company to deliver the certificate(s) to the optionee's stockbroker.

2.5  Termination of Employment; Death

          2.5.1 Except to the extent otherwise provided in Section 2.5.2 or
2.5.3 or in the applicable Plan Agreement, all options and stock appreciation
rights not theretofore exercised shall terminate upon termination of the
grantee's employment for any reason (including death).

          2.5.2 If a grantee's employment terminates for any reason other than
death or dismissal for cause, the grantee may exercise any outstanding option or
stock appreciation right on the following terms and conditions: (a) exercise may
be made only to the extent that the grantee was entitled to exercise the award
on the date of employment termination; and (b) exercise must occur within three
months after employment terminates, except that the three-month period shall be
increased to one year if the termination is by reason of disability, but in no
event after the expiration date of the award as set forth in the Plan Agreement.
In the case of an incentive stock option, the term "disability" for purposes of
the preceding sentence shall have the meaning given to it by sections 22(e)(3)
and 422(c)(6) of the Code.

                                       8

<PAGE>

          2.5.3 If a grantee dies while employed by the Company or any
subsidiary, or after employment termination but during the period in which the
grantee's awards are exercisable pursuant to Section 2.5.2, any outstanding
option or stock appreciation right shall be exercisable on the following terms
and conditions: (a) exercise may be made only to the extent that the grantee was
entitled to exercise the award on the date of death; and (b) exercise must occur
by the earlier of the first anniversary of the grantee's death or the expiration
date of the award. Any such exercise of an award following a grantee's death
shall be made only by the grantee's executor or administrator, unless the
grantee's will specifically disposes of such award, in which case such exercise
shall be made only by the recipient of such specific disposition. If a grantee's
personal representative or the recipient of a specific disposition under the
grantee's will shall be entitled to exercise any award pursuant to the preceding
sentence, such representative or recipient shall be bound by all the terms and
conditions of the Plan and the applicable Plan Agreement which would have
applied to the grantee including, without limitation, the provisions of Sections
3.3 and 3.7 hereof.

2.6  Grant of Restricted Stock

          2.6.1 The Committee may grant restricted shares of Common Stock to
such key persons, in such amounts, and subject to such terms and conditions as
the Committee shall determine in its discretion, subject to the provisions of
the Plan. Restricted stock awards may be made independently of or in connection
with any other award under the Plan, A grantee of a restricted stock award shall
have no rights with respect to such award unless such grantee accepts the award
within such period as the Committee shall specify by executing a Plan Agreement
in such form as the Committee shall determine and, if the Committee shall so
require, makes payment to the Company by certified or official bank check (or
the equivalent thereof acceptable to the Company) in such amount as the
Committee may determine.

          2.6.2 Promptly after a grantee accepts a restricted stock award, the
Company shall issue in the grantee's name a certificate or certificates for the
shares of Common Stock covered by the award. Upon the issuance of such
certificate(s), the grantee shall have the rights of a shareholder with respect
to the restricted stock, subject to the nontransferability restrictions and
Company repurchase rights described in Sections 2.6.4 and 2.6.5 and to such
other restrictions and conditions as the Committee in its discretion may include
in the applicable Plan Agreement.

          2.6.3 Unless the Committee shall otherwise determine, any certificate
issued evidencing shares of restricted stock shall remain in the possession of
the Company until such shares are free of any restrictions specified in the
applicable Plan Agreement.

          2.6.4 Shares of restricted stock may not be sold, assigned,
transferred, pledged or otherwise encumbered or disposed of except as
specifically provided in this

                                       9

<PAGE>

Plan or the applicable Plan Agreement. The Committee at the time of grant shall
specify the date or dates (which may dependupon or be related to the attainment
of performance goals and other conditions) on which the nontransferability of
the restricted stock shall lapse. Unless the applicable Plan Agreement provides
otherwise, additional shares of Common Stock or other property distributed to
the grantee in respect of shares of restricted stock, as dividends or otherwise,
shall be subject to the same restrictions applicable to such restricted stock.

          2.6.5 During the 120 days following termination of the grantee's
employment for any reason, the Company shall have the right to require the
return of any shares to which restrictions on transferability apply, in exchange
for which the Company shall repay to the grantee (or the grantee's estate) any
amount paid by the grantee for such shares.

2.7  Grant of Restricted Stock Units

          2.7.1 The Committee may grant awards of restricted stock units to such
key persons, in such amounts, and subject to such terms and conditions as the
Committee shall determine in its discretion, subject to the provisions of the
Plan. Restricted stock units may be awarded independently of or in connection
with any other award under the Plan.

          2.7.2 At the time of grant, the Committee and/or the Chief Executive
Officer, shall specify the date or dates on which the restricted stock units
shall become fully vested and nonforfeitable, and may specify such conditions to
vesting as it deems appropriate. In the event of the termination of the
grantee's employment by the Company and its subsidiaries for any reason,
restricted stock units that have not become nonforfeitable shall be forfeited
and cancelled. The Committee and/or the Chief Executive Officer at any time may
accelerate vesting dates and otherwise waive or amend any conditions of an award
of restricted stock units.

          2.7.3 At the time of grant, the Committee shall specify the maturity
date applicable to each grant of restricted stock units, which may be determined
at the election of the grantee. Such date may be later than the vesting date or
dates of the award. On the maturity date, the Company shall transfer to the
grantee one unrestricted, fully transferable share of Common Stock for each
restricted stock unit scheduled to be paid out on such date and not previously
forfeited. The Committee shall specify the purchase price, if any, to be paid by
the grantee to the Company for such shares of Common Stock.

2.8  Other Stock-Based Awards

     The Board may authorize other types of stock-based awards (including the
grant of unrestricted shares), which the Committee may grant to such key
persons, and in such amounts and subject to such terms and conditions, as the
Committee shall in its discretion

                                       10

<PAGE>

determine, subject to the provisions of the Plan. Such awards may entail the
transfer of actual shares of Common Stock to Plan participants, or payment in
cash or otherwise of amounts based on the value of shares of Common Stock.

2.9  Stock in Lieu of Cash

     The Committee and/or the Chief Executive Officer may grant awards or shares
of Common Stock in lieu of all or a portion of an award otherwise payable in
cash to an executive officer pursuant to any bonus or incentive compensation
plan of the Company(subject to any applicable limitations in such bonus or
incentive compensation plan). If shares are issued in lieu of cash, the number
of shares of Common Stock to be issued shall be the greatest number of whole
shares which has an aggregate fair market value on the date the cash would
otherwise have been payable pursuant to the terms of such other plan equal to or
less than the amount of such cash.

2.10 Grant of Dividend Equivalent Rights

     The Committee may in its discretion include in the Plan Agreement with
respect to any award a dividend equivalent right entitling the grantee to
receive amounts equal to the ordinary dividends that would be paid, during the
time such award is outstanding and unexercised, on the shares of Common Stock
covered by such award if such shares were then outstanding. In the event such a
provision is included in a Plan Agreement, the Committee shall determine whether
such payments shall be made in cash, in shares of Common Stock or in another
form, whether they shall be conditioned upon the exercise of the award to which
they relate, the time or times at which they shall be made, and such other terms
and conditions as the Committee shall deem appropriate.

                                   ARTICLE III
                                  MISCELLANEOUS

3.1  Amendment of the Plan; Modification of Awards

          3.1.1 The Board may from time to time suspend, discontinue, revise or
amend the Plan in any respect whatsoever, except that no such amendment shall
materially impair any rights or materially increase any obligations under any
award theretofore made under the Plan without the consent of the grantee (or,
after the grantee's death, the person having the right to exercise the award).
For purposes of this Section 3.1, any action of the Board or the Committee that
alters or affects the tax treatment of any award shall not be considered to
materially impair any rights of any grantee.

          3.1.2 Shareholder approval of any amendment shall be obtained to the
extent necessary to comply with section 422 of the Code (relating to incentive
stock options) or other applicable law or regulation.

                                       11

<PAGE>

          3.1.3 The Committee may amend any outstanding Plan Agreement,
including, without limitation, by amendment which would accelerate the time or
times at which the award becomes unrestricted or may be exercised, or waive or
amend any goals, restrictions or conditions set forth in the Agreement. However,
any such amendment that materially impairs the rights or materially increases
the obligations of a grantee under an outstanding award shall be made only with
the consent of the grantee (or, upon the grantee's death, the person having the
right to exercise the award).

3.2  Tax Withholding

          3.2.1 As a condition to the receipt of any shares of Common Stock
pursuant to any award or the lifting of restrictions on any award, or in
connection with any other event that gives rise to a federal or other
governmental tax withholding obligation on the part of the Company relating to
an award (including, without limitation, FICA tax), the Company shall be
entitled to require that the grantee remit to the Company an amount sufficient
in the opinion of the Company to satisfy such withholding obligation.

          3.2.2 If the event giving rise to the withholding obligation is a
transfer of shares of Common Stock, then, unless otherwise specified in the
applicable Plan Agreement, the grantee may satisfy the withholding obligation
imposed under Section 3.2.1 by electing to have the Company withhold shares of
Common Stock having a Fair Market Value equal to the amount of tax to be
withheld. For this purpose, Fair Market Value shall be determined as of the date
on which the amount of tax to be withheld is determined (and any fractional
share amount shall be settled in cash).

3.3  Restrictions

          3.3.1 If the Committee shall at any time determine that any consent
(as hereinafter defined) is necessary or desirable as a condition of, or in
connection with, the granting of any award under the Plan, the issuance or
purchase of shares or other rights thereunder, or the taking of any other action
thereunder (each such action being hereinafter referred to as a "plan action"),
then such plan action shall not be taken, in whole or in part, unless and until
such consent shall have been effected or obtained to the full satisfaction of
the Committee.

          3.3.2 The term "consent" as used herein with respect to any plan
action means (a) any and all listings, registrations or qualifications in
respect thereof upon any securities exchange or under any federal, state or
local law, rule or regulation, (b) any and all written agreements and
representations by the grantee with respect to the disposition of shares, or
with respect to any other matter, which the Committee shall deem necessary or
desirable to comply with the terms of any such listing, registration or
qualification or to obtain an exemption from the requirement that any such
listing, qualification or

                                       12

<PAGE>

registration be made and (c) any and all consents, clearances and approvals in
respect of a plan action by any governmental or other regulatory bodies.

                                       13

<PAGE>

3.4  Nonassignability

     Except to the extent otherwise provided in the applicable Plan Agreement,
no award or right granted to any person under the Plan shall be assignable or
transferable other than by will or by the laws of descent and distribution, and
all such awards and rights shall be exercisable during the life of the grantee
only by the grantee or the grantee's legal representative.

3.5  Requirement of Notification of Election Under Section 83(b) of the Code

     If any grantee shall, in connection with the acquisition of shares of
Common Stock under the Plan, make the election permitted under section 83(b) of
the Code (that is, an election to include in gross income in the year of
transfer the amounts specified in section 83(b)), such grantee shall notify the
Company of such election within 10 days of filing notice of the election with
the Internal Revenue Service, in addition to any filing and notification
required pursuant to regulations issued under the authority of Code section
83(b).

3.6  Requirement of Notification Upon Disqualifying Disposition Under Section
     421(b)of the Code

     If any grantee shall make any disposition of shares of Common Stock issued
pursuant to the exercise of an incentive stock option under the circumstances
described in section 421(b) of the Code (relating to certain disqualifying
dispositions), such grantee shall notify the Company of such disposition within
10 days thereof.

3.7  Right of Discharge Reserved

     Nothing in the Plan or in any Plan Agreement shall confer upon any grantee
the right to continue in the employ of the Company or affect any right which the
Company may have to terminate such employment.

3.8  Nature of Payments

          3.8.1 Any and all grants of awards and issuances of shares of Common
Stock under the Plan shall be in consideration of services performed for the
Company by the grantee.

          3.8.2 All such grants and issuances shall constitute a special
incentive payment to the grantee and shall not be taken into account in
computing the amount of salary or compensation of the grantee for the purpose of
determining any benefits under any pension, retirement, profit-sharing, bonus,
life insurance or other benefit plan of the Company or under any agreement
between the Company and the grantee, unless such plan or agreement specifically
provides otherwise.

                                       14

<PAGE>

3.9  Non-Uniform Determinations

     The Committee's determinations under the Plan need not be uniform and may
be made by it selectively among persons who receive, or are eligible to receive,
awards under the Plan (whether or not such persons are similarly situated).
Without limiting the generality of the foregoing, the Committee shall be
entitled, among other things, to make non-uniform and selective determinations,
and to enter into non-uniform and selective Plan agreements, as to (a) the
persons to receive awards under the Plan, (b) the terms and provisions of awards
under the Plan, and (c) the treatment of leaves of absence pursuant to Section
1.6.4.

3.10 Other Payments or Awards

     Nothing contained in the Plan shall be deemed in any way to limit or
restrict the Company from making any award or payment to any person under any
other plan, arrangement or understanding, whether now existing or hereafter in
effect.

3.11 Section Headings

          The section headings contained herein are for the purpose of
convenience only and are not intended to define or limit the contents of the
sections.

3.12 Effective Date and Term of Plan

          3.12.1 The Plan was adopted by the Board and the Company's
shareholders on August 21, 1997, but effective as of November 14, 1996. All
awards under the Plan prior to such shareholder approval are subject in their
entirety to such approval. If such approval is not obtained prior to the first
anniversary of the date of adoption of the Plan, the Plan and all awards
thereunder shall terminate on that date.

          3.12.2 Unless sooner terminated by the Board, the provisions of the
Plan respecting the grant of incentive stock options shall terminate on the day
before the tenth anniversary of the adoption of the Plan by the Board, and no
incentive stock option awards shall thereafter be made under the Plan. All
awards made under the Plan prior to its termination shall remain in effect until
such awards have been satisfied or terminated in accordance with the terms and
provisions of the Plan and the applicable Plan Agreements.

3.13 Governing Law

          All rights and obligations under the Plan shall be construed and
interpreted in accordance with the laws of the State of Delaware, without giving
effect to principles of conflict of laws.

                                       15

<PAGE>

                     Amendments to 1997 Stock Incentive Plan

..    The number of shares of common stock available under awards shall be
     increased (pre-stock split) to 12,500,000.

..    On January 1 of each year, commencing on January 1, 2001, the number of
     shares of common stock of Arbinet available for issuance shall be increased
     by the least of:

          .    2,000,000 shares
          .    3% of the outstanding shares of common stock; or
          .    a number of shares determined by the board.

..    Administration of plan. The plan will be administered by the Compensation
     Committee.

..    Vesting period and expiration date of options. The CEO (in addition to the
     Compensation Committee) will have authority to determine the vesting period
     and expiration date of options.

..    Stock in lieu of cash. The CEO and the Compensation Committee will be
     authorized to grant awards of common stock to executive officers of Arbinet
     in lieu of all or a portion of an award otherwise payable in cash pursuant
     to any bonus or other plan, based on the fair market value of Arbinet's
     common stock.